Scientists and forecasters are mostly in agreement that major storms will be less frequent but stronger

The debate about whether climate change is affecting the frequency and intensity of tropical storms and hurricanes is not new.

After 2004’s “Mean Season,” and the record-breaking 2005 season, it became the hottest of topics, and the subject of a spirited debate, among scientists, forecasters and emergency managers. That hasn’t abated, and some of those debaters went at it again Thursday at a packed session of the Florida Governor’s Hurricane Conference, meeting this week in Orlando.

There’s still disagreement, but minds mostly have come into line on some key points:

*Major storms — Category 3 or higher on the Saffir-Simpson Scale, with top sustained winds of at least 111 mph — will be less frequent but stronger.

*Rising sea levels and warmer ocean temperatures bring a higher risk of storm surge damage, likely the greatest threat to coastal communities from climate change. Surge is causing increased flooding in low-lying areas and will only get worse.

*Rainfall and its subsequent flooding likely will increase.

*The spot on the planet where storms reach their full intensity likely is moving north.

“Even if the climate were identical from one year to the next, we’d have a different number of hurricanes by chance,” said Kerry Emanuel, professor of atmospheric science at the Massachusetts Institute of Technology.

Emanuel said future generations can handle each crisis as it occurs or take steps today, such as modifying power plants to reduce carbon in the atmosphere.

“It will be cheaper than if we have to cope with these disasters on an increasing level,” he said.

But Emanuel also said he believes the effect on storms from carbon dioxide in the atmosphere and warmer ocean waters goes only so far.

“It plateaus,” he said. “The thing that controls hurricanes does not keep going up.”

Gabriel Vecchio, part of a National Oceanic and Atmospheric Administration research group on climate change, said studies and simulations suggest the frequency and intensity of storms have fluctuated wildly over the centuries and even millennia.

But he cited a study — albeit with a substantive margin of error — showing a 40 percent decrease in Category 1 storms, a slight decrease in 2s and 3s, and “a substantial increase” in 4s and 5s.

“Even if there is no climate change, which there is, and even if climate change doesn’t affect hurricanes, which it may,” Vecchio said, “there’s reason to believe the future may not be a reflection of the past.”

Brian Soden, a professor at the University of Miami’s Rosenstiel School of Marine and Atmospheric Science, said there’s no clear trend as to whether climate change is affecting where storms strike. He also said studies suggest it’s not making storms form earlier He said research suggests the year’s first storm is birthing a week and a half later than it did 50 years ago.

The most powerful, frequently discussed and disturbing part of the conversation was storm surge.

Vecchio said studies show sea levels have risen about 9 inches just in the past century.

“There’s no ambiguity about this,” he said. “And we know this rise in sea level is due to human activity. We’re already seeing the impacts.”

He cited Miami Beach’s South Beach, where streets regularly flood with sea water at high tides.

Vecchio showed an illustration of the globe in 2100 in which sea levels have risen 4-1/2 feet and all of peninsular Florida is under water.

Soden displayed a simulation showing that, in 1992, Hurricane Andrew’s 15-foot storm surge banged into southeast Florida’s coastal ridge and had limited impact.

“Take the same storm. Add 3 feet of sea level rise. Now the water can get over that ridge,” Soden said. “And once you’re over that ridge, it’s downhill all the way to Naples. The southern two-thirds of Dade (Miami-Dade) County would be under water.”

POSTED BY: Emergency Management / Eliot Kleinberg

SOURCE: Tribune Content Agency, LLC

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